Process and device for solidifying pitches, bitumina and the like



June 1962 H. KRIEGER ET AL 3,037,239

PROCESS AND DEVICE FOR SOLIDIF'YING PITCHES, BITUMINA AND THE LIKE Filed Nov. 24, 1959 2 Sheets-Sheet 1 FIG. I.

INVENTORS HANS KRiEGER ERICH SCHWEYM Y JULIUS GELLER DEZSOE STEINHERZ AT TOR N EY.

2 Sheets-Sheet 2 ATTORNEY.

INVENTORS HANS KRIEGER ERICH SCHWEYM JULIUS GELLER DEZSOE STEINHERZ J1me 1962 H. KRIEGER ET AL PROCESS AND DEVICE FOR SOLIDIFYING PITCHES, BITUMINA AND THE LIKE Filed Nov. 24, 1959 United States Patent 3 037,239 PROCESS AND DE' VICE FOR SOLIDIFYING PITCHES, BITUlVIINA AND THE LIKE Hans Krieger and Erich Schweym, Castrop-Rauxel, and

Julius Geller, Bad Hamburg vor der Hohe, Germany,

assignors to Riitgerswerlre-Aktiengesellschaft, Frankfurt am Main, Germany Filed Nov. 24, 1959, Ser. No. 855,167 6 Claims. (Cl. 182.4)

This invention relates to a process and a device for converting pitches and bitumina from the liquid molten state into the solid state, by cooling with a liquid medium, and is a continuation-in-part of Serial No. 510,73 8, filed May 24, 1955, and now abandoned.

It has been known that in order to convert crystallizable molten masses or liquid plastic masses into the solid state, these substances are introduced into large pans, in which said substances slowly cool and solidify during a period of one or more days. The solidified contents of these pans have then to be removed by troublesome manual work, e.g. by means of a hoe. It hasalso been suggested to pour such substances in liquid condition to the outer surface of slowly rotating cooling drums in a thin layer, whereby, the cooling period can be reduced to a few minutes. However, the yield of such devices is limited and the devices are relatively expensive.

In another known cooling process, liquid plastic masses are introduced into stagnant water or water of laminar flow in order to obtain thin filaments, or the like, of said plastic masses.

Particular difficulties, such as the evolution of vapors which are injurious to health and contact with materials which may have adverse or dangerous effects on human skin, are encountered in the solidification of pitches and similar bituminous materials, which are obtained as molten residues of distillation processes, in large quantities. It is a main object of the present invention to convert such materials by cooling into solid transportable form, with the elimination of said dilficulties and in simple and economical manner with a high throughput of the equipment used.

The process of the invention can be applied to the cooling and solidification of any kind of pitches and bituminous materials, e.g. pitches from coal tar, brown coal tar and other tars, distillation residues of mineral oils and mineral oil products, asphalts, bitumens and the like. In carrying out the process of the present invention the preferred cooling medium is water, to which the invention is not limited. It has been found that in proceeding according to the present invention in the manner described hereinafter no inclusions of cooling fluid in the solidified material are formed.

According to the present process the substance to be solidified is continuously introduced in liquid condition into a liquid cooling medium and is subjected to cooling by said medium in such a manner that the cooling medium surrounds the substance to be solidified on all sides until the substance acquires the desired stability of shape.

In carrying out the process of this invention the hot, molten material to be solidified is introduced through a heated nozzle, as a molten jet of about 2030 mm. diameter into, and passed through, a flowing stream of the cooling medium, axially in the direction of flow of the latter, said stream of the cooling medium being caused to flow with turbulence. The heated nozzle is thereby centrally arranged within the cooling medium of turbulent flow. The velocity of flow of said stream of cooling medium is somewhat higher than the velocity of the flowing material discharged from the heated nozzle. The flowing stream of cooling medium, into which the molten jet of the material to be cooled is discharged, is thereby passed through a tube which is completely filled with the turbulently flowing stream of cooling medium.

In carrying out the invention in this manner, the turbulent stream of moving cooling medium is utilized for transportation of the material to be solidified. Due to the somewhat higher velocity of flow of the cooling medium, the jet of the material to be solidified will be drawn away from the discharge opening of the nozzle to an extent which is sufiicient for avoiding stowing as well as constriction, furthermore the jet will be centered in the stream of cooling liquid and transported by it.

As soon as the substance treated is in sufficiently solidified condition within the cooling medium, it can be taken up, after leaving the tube, by a conventional conveyor device arranged partially within, or outside of an after-cooling bath.

Furthermore, the substance cooled according to the present invention can be treated, after having acquired a sulficient stability of shape, in the manner described in the German Patent 688,505 by separating the substance prior to its complete cooling and solidification from the cooling medium and subsequently subjecting it to cooling by air, whereby the adhering cooling medium is caused to evaporate by the residual inherent heat of the substance. In this procedure the core of the strand may be still in plastic condition prior to the cooling by air. Therefore it is easily possible to subject the strand prior to, or during the subsequent cooling by air, and prior to the complete solidification, to plastic molding. This possibility can be utilized for storing the strand by the application of suitable deflection in the form of rings or to join several strands for storage on a common conveying device.

The substance to be solidified can be introduced into the cooling medium by gravity or under increased pressure. The discharge velocity of the substance from the discharge nozzle arranged within the cooling medium, is determined by the pressure.

The appended drawings diagrammatically illustrate by way of example some specific embodiments of devices and best modes for carrying out the invention, to which the invention is not limited.

In the drawings FIGURES 1 and 2 diagrammatically illustrate two embodiments of devices for carrying out the invention;

FIGURE 3 diagrammatically illustrates a discharge nozzle, on a larger scale, and

FIGURE 4 illustrates a device in which several cooling tubes are used.

Referring now to the drawings in detail, in FIG. 1 the hot substance to be solidified is introduced through tube 2 into nozzle 3, which is surrounded by an open heating jacket 4. The heating liquid, e.g. hot water, enters jacket 4 through tube 5. The cooling medium, e.g. water, is introduced through tube 10 into cooling tube 14 and mixes in the latter behind the nozzle 3 with said heating means. The cooling medium and the jet of the substance to be solidified are caused to pass through cooling tube 14, whereby the velocity of the cooling liquid is higher than that of the jet of the substance to be solidified.- At the end of the cooling tube 14 an inclined screen 15 is arranged, through which the cooling medium flows to vessel 16. The cooled jet or strand is caused to pass to conveyor 17 and can be sprayed here, if desired, by a spray 18 with cooling liquid. From conveyor 17 the solidified strand is discharged, e.g. to a railroad car 12. Vessel 16 contains a filter for separating small particles of solidified substance from the cooling fluid. Through tube 7 the pump 8 draws off the 3 cooling liquid from vessel 16 and forces the liquid through cooler 9 and tube 10 to cooling tube 14.

In order to increase the throughput, several nozzles 3 and cooling tubes 14 provided with the necessary accessories, can be caused to operate in the above described manner and discharge to screen 15 and conveyor 17. Furthermore, several nozzles 3 can be arranged in a single tube 14 in order to cause two or more spaced jets to pass in parallel direction simultaneously through cooling tube 14.

The embodiment illustrated in FIG. 2, is a modified form of the device shown in FIG. 1. While in FIG. 1 the heating jacket of the nozzle is open and the heating means escaping from the nozzle jacket enters the cooling medium, in FIG. 2 the nozzle 3 is provided with a closed cooling jacket, into which the heating means is introduced through tube and from which the heating means is discharged through tube 20. Instead of heating in this manner, the nozzle can be heated electrically. In the arrangement shown in FIG. 2, only a portion of the circulating cooling medium is caused to pass through cooler 9. The rest of the circulating cooling medium is introduced through tube 21 into tube 14, near nozzle 3. The cooling medium which passes through cooler 9, is introduced into tube 14 some distance behind nozzle 3. The proportion between the uncooled portion and the cooled portion of the cooling medium, in vessel 16 can be adjusted within Wide limits by means of adjusting members (not shown in FIG. 2) arranged in the tubes.

The cooling medium can be introduced at various points into the cooling tube 14. It is contemplated according to the invention to introduce the cooling medium e.g. through an individual tube, or through several supply tubes uniformly distributed and tangentially or radially arranged on the periphery of the cooling tube.

Nozzle 3 can be aranged in axially displaceable man ner in cooling tube 14.

FIGURE 3 illustrates a discharge nozzle for use in an apparatus of the type shown in FIGS. 1 and 2. Nozzle 3 is provided with a heating jacket 4, which is open at the mouth of the nozzle. The heating means for jacket 4 enters at 5 and is discharged from the jacket at the mouth of the nozzle in the same direction as the molten substance discharged from the nozzle.

The flowing cooling medium is introduced at 13 into cooling tube 14, which surrounds the nozzle. The nozzle, heating jacket and the cooling tube are arranged concentrically relative to each other. It is of advantage to provide nozzles of this type having a heating jacket, which are in direct contact with the cooling medium, with a heat insulating layer on the outer surface.

The substance surrounded by the warm heating means in the nozzle jacket, and the cooling medium, the temperature of which is sufficiently below the solidification temperature of said substance, flow in the same direction through cooling tube 14. Thereby, the heating means discharged from the nozzle jacket is gradually mixed with the cold stream of cooling medium. The proportion of the heating means and cooling medium, as well as their temperatures, are adjusted relative to each other in such a manner that the temperature of the resulting mixture is sufiiciently below the solidification temperature of the molten substance to be cooled If acceleration of the flow in tube 14 is desired, the diameter of this tube is reduced e.g. over a constriction b from a to c in FIG. 3. On the other hand, in order to reduce the velocity of the flow, the diameter of the cooling tube is increased over an extension d, e.g. from a to e, as shown in dash-and-dot line in FIG. 3.

In the embodiment diagrammatically illustrated in FIGURE 4, one current of the substance to be solidified, or several currents thereof conducted in parallel, are introduced through heated discharge openings first into a cooling medium which is caused to flow with somewhat higher velocity as that of the substance, and said substance and cooling medium are caused to move together until the substance acquires a sufiicient stability of its shape. Subsequently, i.e. after the substance has reached this condition, the substance, as well as the cooling medium are discharged from the tubes into a cooling vessel, in which the substance to be solidified is caused to slowly move within a cooling medium, for further cooling. Finally, in order to obtain complete solidification and to remove by drying particles of the cooling medium adhering to the surface of the substance, the latter is caused to move in the air on a certain distance.

It is of decisive importance that in the arrangement illustrated in FIGURE 4 and described further below, the device be quickly adjustable to changes of the working conditions, for example changes of the initial temperature of the substance to be solidified. The throughput capacity of the apparatus shown in FIGURE 4 should be likewise adjustable to changing conditions. This requires the possibility of adjusting the cooling capacity and throughput capacity by simple means. According to the invention, the latter consist in the arrangement of a shutoff means in the supply tube of the cooling medium directly before the entrance to the cooling path, as well as in the supply tube of the substance to be solidified directly before the entrance to the nozzle, in order to obtain fine adjustment of the supply of cooling liquid as well as the substance to be solidified, respectively, if desired.

In the solidification of certain molten substances, e.g. hard pitch, which have a relatively high solidification temperature, said substances may show the tendency to crack at a too high difference in temperature of the substance and cooling medium, respectively, such cracking being caused by thermal stresses in the interior of the solidifying substance and its brittleness. This undesired effect can be eliminated according to the invention by preheating the cooling medium to an extent which depends on the character of the substance to be solidified and its initial temperature. The use of the preheated cooling medium prevents quenching of the substance to be solidified, but still causes sufficient cooling thereof.

At relatively high initial temperatures of the substance to be solidified, it has been found to be of advantage to subject the substance to a preliminary cooling. This can be done by allowing the substance to stand and cool in a storage container until it has the desired initial temperature and then supply said substance for further cooling to the cooling device. In order to carry out this procedure continuously, in general two storage containers are necessary for alternate use, whereby one of the storage containers is used for feeding the substance to the cooling device, while in the other storage container the substance is allowed to cool. By this simple procedure the initial temperature of the substance to be solidified is gradually reduced, whereby care should be taken that the temperature of the substance in the storage container remains sufficiently high in order to carry out the process of the invention.

In the case of substances, in the solidification of which constant conditions of cooling are essential, it is more advantageous to start cooling at a temperature which is too high in itself and to extract by a particular precooling device such an amount of heat as necessary for the adjustment of the desired constant level of temperature. In this connection it is contemplated according to the invention to pass the substance to be solidified on its way from the storage container to the cooling device through a heat exchanger, the cooling effect of which is adjustably controlled by the temperature of the substance to be solidified. Thereby the temperature of the substance in the storage container, as well as the temperature at the admission of the substance to the devices for preliminary cooling, or the temperature at the discharge from said devices, is used as the condition for controlling the supply of the cooling means to the device for preliminary cooling. The cooling means proper is conducted in circulation, if desired with recooling or preheating.

In the device diagrammatically shown in FIGURE 4, the hot, liquid substance to be solidified flows either through the preliminary cooler 2, or directly to a distributor 3 and is supplied from the latter through tubes 4, which are conducted in parallel and the ends of which are provided with heated discharge nozzles 5, into a corresponding number of cooling tubes 6, through which a coolingmedium flows. Each of the heated discharge nozzles for the substance to be solidified, discharges the substance within a tube 6, through which the cooling medium flows.

Upon entering the cooling medium in tubes 6, the molten substance is moved by the cooling medium of turbulent flow, which flows with a somewhat higher velocity than that of the discharge velocity of the molten substance from nozzles 5.

On its way through the cooling tubes, the substance gradually solidifies and attains sufiicient stability of its shape. In this condition it escapes from the cooling tubes together with the cooling medium and passes over the chutes 7 to a conveyor device 8, which is arranged in a cooling vessel 9. This cooling vessel 9 is filled to a suitable height with a cooling medium. The conveyor device 8 is located at the supply point for the substance to be solidified, completely within the cooling medium, but ascends after a certain distance from the cooling medium. Thus, the substance which is discharged from the cooling tubes and is not completely solidified yet, is now caused by the conveyor 8 to move within the cooling medium in the cooling vessel 9. The substance removed from the cooling medium by the ascending conveyor is now caused to move in contact with air on a path of predetermined length and on this path final solidification and separation from the superficially adhering particles of cooling medium takes place, whereupon the substance is discharged for example to a railroad car 10.

1 ing medium, which may be necessary in special cases,

can be efiected either through direct supply of steam over valve member 16, or over a heat exchanger 17.

In the arrangement of FIGURE 4, two circulations of the cooling medium are shown which are brought about by a pump 18. One current of the cooling medium is conducted from cooling vessel 9 over a heat exchanger 17 (which serves as a cooler or preheater) into cooling tubes 6, from which it return to vessel 9. Another current of the cooling medium escapes from nozzles 19 as shown in FIGURE 4 and after cooling by air flows back to vessel 9. The proportion between these two branch currents can be adjusted within wide limits by adjusting members arranged in the conduits. A preheating of the cooling medium flowing in the cooling tubes, may be necessary in the case of certain substances to be solidified, such as hard pitch, at the beginning of the cooling. However, in the course of further cooling the cooling medium absorbs heat from the substance to be solidified until an equilibrium is reached in which the amount of heat absorbed is equal to the losses of heat, whereby the cooling medium is warmed to such an extent that in general an additional preheating thereof can be dispensed with.

From the circulation of the cooling medium for the cooling tubes 6, over tube 20 and adjusting valve 21 a further partial current is branched ofi? for the preliminary cooler 2 for the substance to be solidified and this branch current is returned to vessel 9 over tube 22. As shown in FIGURE 4 this partial current is always adjusted from a temperature contact means 23 arranged in distributor 3, over temperature regulator 24, by regulating valve 21 in such a manner that the temperature of the substance to be solidified always remains constant in distributor 3 so that the feed temperature of the substance to nozzles 5 remains always constant.

It will be understood that all pipes, conduits and the like, through which the material to be solidified is supplied to the cooling device of the invention, must be provided with means for heating said pipes, etc. and must be connected with means for passing a scavenging material, e.g. steam, through said pipes, etc. for emptying them in the direction of the nozzles.

In order to discover disturbances and for the fast elimination of the latter, it has been found to be of advantage if the introduction of the substance to be solidified into the cooling medium can be visually observed for a certain distance. This can be preferably attained by having in the cooling tube 6 in the range of nozzles 5 intermediate pieces 26 of transparent material which can be quickly inserted and removed by means of rapid connecting means.

Example 1 The cooling device used was similar to that diagrammatically illustrated in FIGURE 1 and included a cooling path of 47 m. in length with two semi-circular arcs having a radius of 1.4 m. and 0.65 m., respectively. The diameter of the cooling tube was 80 mm. The discharge nozzle for the supply of the substance to be cooled was provided with a heating jacket which was open at the mouth of the nozzle. The diameter of the opening for the substance to be cooled amounted to 28 mm. and the substance to be cooled was coal tar pitch having a softening point of 68 C. Hot water was used for heating the nozzle and cold water was used as the cooling medium. The pitch cooled in the cooling tube and the cooling medium were introduced after discharge from the cooling path for further cooling into an aftercoo1ing vessel, from which the solidified pitch was removed by means of a conveyor, part of which was located within the water in said vessels.

Cooling was carried out under the following conditions.

Temperature of the pitch 143 C. Heating of the nozzle:

Temperature of the heating Water 92 C. Amount of hot water 1.2 m. /h. Cooling:

Temperature of cold Water 15 C. Amount of cold water 43 m. /h. Temperature of the mixed water:

Without pitch 17 C. With pitch 18 C. Velocity of water in the cooling tube 2.58 m./second. Pressure in the container for the substance to be solidified 0.8 atmosphere excess pressure. Pressure at the nozzle mouth"--- 0.5 atmosphere excess pressure. Velocity of conveyor 3 m./minute. Cooling path under water in the after-cooling vessel 4 m.

1 corresponds to a Reynolds number -200,000.

The cooled and solidified pitch was obtained in the form of massive strands of about 25 mm. diameter, which had no cavities and were weakly corrugated on their surface. The throughput amounted to 3.5 tons (t.) per hour (h.).

7 Example 2 The process of this example was carried out in apparatus corresponding to the principle and arrangement diagrammatically illustrated in the appended FIG. 4. This apparatus includes a reservoir 1 for the pitch to be solidified, said reservoir having a capacity of about 150 tons. The pitch, e.g. coal tar pitch, which has a temperature of about 180 C. flows by gravity through a heated conduit to distributor 3, which is likewise heated and is arranged at a distance of about m. from the average level of the pitch in container 1. Through the distributor 3, over heatable conduits 4, twelve separately arranged, electrically heated pitch nozzles 5 are fed. The discharge opening of these nozzles amounts to mm. The nozzles are centrally arranged in twelve individual, parallel cooling tubes 26. These cooling tubes have an inner diameter of 65 mm. and each has a length of m. At the end, each of these tubes is deflected by 180 by means of a tube turn, the radius of which amounts to 1.20 m. All of these tubes discharge to a single inclined plane of suitable dimensions, which passes the cooling water to cooling vessel 9 containing about 700 m. of water and passes the solidified jets of pitch to a conveyor belt of about 35 or. length, of which a part of 15 m. is arranged below the water level in container 9. The water in vessel 9 is filtered through a coke filter and is reintroduced by means of a centrifugal pump 18 having a feed performance of 350 m. /hour into the twelve cooling tubes 6 in a cycle. A part of the circulating water is sprayed for cooling by air through twenty nozzles 19.

The operating data of the above described apparatus are as follows:

Temperature of the pitch 180-190 C. solidification point of the pitch 80 C. Heating of the nozzles Electrical. Temperature of the heated nozzles About 120 C. Amount of cooling water for 20 tubes Amount of cooling water for 1 tube Velocity of cooling water in the tube 240 m. /hour.

20 m3/ hour.

1.7 m./sec.

Reynolds number of the cooling water flow In the above described apparatus pitch jets of 20 mm. thickness are produced. The throughput of one nozzle is 2 to/hour and of the entire apparatus 24 to/hour.

It will be understood from the above that in the process of this invention solidfication is brought about by cooling the starting material to a temperature below its solidification point. Such material is discharged through a centrally arranged nozzle having a temperature at which no solidfication by cooling occurs, into a tubular cooling device substantially completely filled with a cooling liquid of turbulent flow, said cooling liquid flowing with a sufliciently higher velocity than the molten material, so that the cooling liquid draws along the molten material in centered condition in the cooling tube and prevents stowing as well as constrictions at the opening of the nozzle. The molten material is subjected to cooling in form of jets of 20 to 30 mm. o and more in tubes e.g. of 65 to mm. whereby e.g. 2 tons per hour and nozzle and more of the molten material can be solidified. The cooling tube may be straight or bent, as described above and shown in the drawings. In solidfying coal tar pitch according to the process of the invention a cooling tube of, for example, 20 and more meters can be used, which is provided with a bent portion having a radius of curvature of about 2 meters. The flowing velocity of the cooling liquid may be in the range of 1.7 to 4 m./sec. The use of cooling tubes completely filled with the flowing cooling liquid is necessary in order to secure proper centering of the jet-shaped material passing through a cooling tube which has a length of, for example, 20 meters and may be straight or have a curved shape or curved portions. Instead of water, suitable aqueous liquids which are inert to the material to be solidified and to the apparatus, can be used.

The term turbulent fiow is used herein in its conventional meaning as defined in the art, e.g. Perry, Chemical Engineers Handbook, 3rd ed. (1950), page 375, right col., paragraph 5.

It will be understood from the above "that this invention is not limited to the materials, conditions, proportions, structures, steps, and other details specifically described above and illustrated in the drawings and can be carried out with various modifications without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. A process for converting a material selected from the group consisting of pitches and bitumina from liquid molten state into the solid state, comprising discharging into a tubular cooling device substantially filled by a streaming aqueous cooling liquid of turbulent flow, said material in molten condition in form of a jet of about 20 to 30 mm. through a heated discharge tube centrally arranged relative to said device, in the direction of flow of the cooling liquid, the velocity of flow of said cooling liquid being higher than the velocity of discharge of the material to be cooled, in order to cause cooling and passage of said material over a substantially central cooling path in axial direction through said device, until the desired cooling and solidification is attained, said cooling liquid having a temperature below the solidification point of the starting material to be treated.

2. A process as claimed in claim 1, in which the mate rial to be treated is brought in contact with aqueous liquid having a temperature above the solidification point of said material, immediately after its discharge into said device, on a limited length. of the cooling path and subsequently said aqueous liquid is mixed with the streaming liquid to a mixture having a temperature below the solidification point of the material.

3. A process as claimed in claim 1, in which the material to be treated is heated during its discharge into the tubular cooling device.

4. A process as claimed in claim 1, in which the material to be solidified is separated from the flowing cooling liquid prior to complete solidification.

5. A process as claimed in claim 4, in which the material separated from the flowing cooling liquid is subjected to after-cooling in a substantially stagnant liquid cooling medium and is finally cooled in the air until complete solidification is attained.

6. An apparatus for converting a material selected from the group consisting of pitches and bitumina from liquid molten state into the solid state, comprising a tubular device for effecting cooling of a molten stream of said material by direct contact of a streaming aqueous cooling liquid of turbulent flow; means for discharging a jet of molten material in substantially central, axial direction into said tubular device and means for heating said discharging means; means for cooling and circulating said References Cited in the file of this patent UNITED STATES PATENTS Schol Nov. 22, 1932 10 Fehr et a1. Nov. 8, 1938 Bartholomew Aug. 13, 1940 Breedis Aug. 10, 1943 Roberts Jan. 2, 1951 Mitchell et a1. Mar. 3, 1959 Krohma Mar. 24, 1959 

1. A PROCESS FOR CONVERTING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF PITCHES AND BITUMINA FROM LIQUID MOLTEN STATE INTO THE SOLID STATE, COMPRISING DISCHARGING INTO A TUBULAR COOLING DEVICE SUBSTANTIALLY FILLED BY A STREAMING AQUEOUS COOLING LIQUID OF TURBULENT FLOW, SAID MATERIAL IN MOLTEN CONDITION IN FORM OF A JET OF ABOUT 20 TO 30 MM. $ THROUGH A HEATED DISCHARGE TUBE CENTRALLY ARRANGED RELATIVE TO SAID DEVICE, IN THE DIRECTION OF FLOW OF THE COOLING LIQUID, THE VELOCITY OF FLOW OF SAID COOLING LIQUID BEING HIGHER THAN THE VELOCITY OF DISCHARGE OF THE MATERIAL TO BE COOLED, IN ORDER TO CAUSE COOLING AND PASSAGE OF SAID MATERIAL OVER A SUBSTANTIALLY CENTRAL COOLING PATH IN AXIAL DIRECTION THROUGH SAID DEVICE, UNTIL THE DESIRED COOLING AND SOLIDIFICATION IS ATTAINED, SAID COOLING LIQUID HAVING A TEMPERATURE BELOW THE SOLIDIFICATION POINT OF THE STARTING MATERIAL TO BE TREATED. 